On Sun, 12 Oct 2003 13:11:08 -0700, "Simon Cooke" <[EMAIL PROTECTED]> wrote:
> From: "Nev Young" <[EMAIL PROTECTED]> > > If it is a read of the ROM then you need to assert ROMCSL & ROMCSRL to > > turn off the ROM. Dunno if you could do that fast enough to be > effective > > within one read cycle though. > > > > I'm sure some one will be along in a moment to prove me wrong. > > *cough* > > ;-) > > Yeah, you can. That's how the MultiROM worked :) > But I thought that with the MultiROM the internal ROM was off. If I understand correctly Adrian wants to put data on the CDn lines between MREQL going low and RDL going low. The ROM may not go tristate fast enough to prevent a clash on the CDn lines. This was the problem I had with UniDos in the PlusD and DISCiPLE when I tried to switch the ROM out during a RST8. I had to get round it by having the same instruction in both the (speccy)ROM and the PlusD shadow ROM. As I wrote before if he's fighting RAM then there's no problem. Nev -- Nev - please note that mail to address nevilley@ will now go into a spam bucket because of excessive mail abuse. Please use one of the new addresses.
